1. Field of the Invention
The present invention relates generally to a recording apparatus, reproducing apparatus, recording method and reproducing method in which upon recording or reproducing data by rotating a recording medium, data is recorded or reproduced at least during an inertial rotation of the recording medium after the control of the rotation thereof is interrupted based on data amount for recording or reproducing.
2. Description of the Related Art
According to a conventional technology, in order to prevent an interruption of reproduction of audio data due to an interruption of reading of the audio data from a recording medium which is caused by vibration or the like during reproduction of the audio data recorded in the recording medium, for example, a spindle motor is rotated at a higher speed than a rotation speed necessary for ordinary reproduction so as to reproduce the audio data more rapidly than the reproduction speed usually necessary for the reproduction. Then, audio data processed by a signal processing portion is stored in a buffer RAM temporarily from RAM (random access memory) controller and even if reading of the audio data from the recording medium is interrupted due to vibration or the like, the data is read continuously from the buffer RAM at a predetermined speed under a control of a microcomputer.
According to the conventional technology for preventing an interruption of reproduction of audio data due to vibration or the like, the audio data is reproduced from the recording medium rapidly by rotating the spindle motor at a high speed and written into the buffer RAM. If data remaining in the buffer RAM becomes short, new data is written therein each time. Thus, if the buffer RAM is full, the microcomputer has to interrupt write of the audio data by the RAM controller and change into a pose operation or the like. However, during such a pose operation, the spindle motor remains in a rotating condition, laser beam from an optical pickup remains irradiated to an optical disc and further, PLL (phase locked loop) of the servo system is kept locked. Thus, there is such a disadvantage that power consumption increases by an amount corresponding to power consumption by the pose operation as compared to ordinary rotating operation time.
If acceleration of the spindle motor and write into the buffer RAM are controlled at the same timing, write into the buffer RAM is disabled except when the spindle motor is accelerated. Thus, there is another disadvantage that it takes long to write into the buffer RAM.
In a conventional servo system PLL shown in FIG. 1, an output of the RFCK (read frame clock) 47 based on a stabilized frequency from a crystal oscillator 41 and an output of the WFCK (write frame clock) 48 generated from a rotation of a disc 40 are compared each other by a phase comparator 49. This result is called phase measurement 50, and phase measurement 50 and period measurement 51 are mixed to produce a disc speed control signal through a speed/phase changeover 52. This disc speed control signal is inputted for disc drive to control a disc speed. Before the above described control system is actuated, a disc rotation speed is controlled to near a predetermined value depending on a disc speed control output outputted by the speed/phase changeover 52 based on a result of measurement of the rotation speed of the disc 40 by the speed measurement 46. A clock for use in a signal processing block 53 is applied after processing an output of the crystal oscillator 41 by a signal processing reference clock generating circuit 45. As a result, only when the frequency of a signal reproduced from a recording medium is within a capture range which is a limited frequency range around 4.3218 MHz as shown in FIG. 2, a reference clock generated from the crystal vibrator can be processed. Consequently, there is such a problem that a strict speed control is necessary to drive the recording medium.
Accordingly, the present invention has been achieved in views of the above described problems and an object of the invention is to provide a recording apparatus and a reproducing apparatus capable of saving electric power when preventing an interruption of reproduction of audio data due to vibration or the like.